The technology described herein relates to graphics processing systems and in particular to methods of and apparatus for taking account of the effect of shadows when rendering images for display.
When rendering images, such as output frames, for display in graphics processing systems, it is often desirable to take account of the effect of shadows in the scene being rendered.
The Applicants have previously proposed in their GB Patent Application GB-A-2525636 a technique that is particularly suitable for taking account of the effect of shadows on “diffuse” lighting (i.e. non-directional, “matte” lighting) when rendering images (frames) for output.
However, as well as determining the effect of shadows on “diffuse” lighting in an image being rendered, it would also be desirable to consider and take account of the effect of shadows in relation to “specular” lighting (i.e. sharp, “mirror-like” highlights) in an image being rendered. This can be more difficult to achieve than when considering shadows in relation to “diffuse” lighting, because, for example, depending on the lit material, a specular highlight may be caused by a very small part of a light source, and/or materials with sharp specular highlights can tend to give rise to high-frequency lighting variations (in contrast to diffuse lighting which will tend to give rise to lower frequency lighting variations).
The Applicants accordingly believe that there remains scope for improved techniques for taking account of the effect of shadows on specular lighting in an image being rendered in graphics processing systems.
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